He says so himself, virtually, in his answer to the notice of his nomination to the Confederate presidency.

Some of his generals have said so in their writings since the downfall of the Confederacy.
My recollection is that my first orders for the battle of Chattanooga were as fought.

Sherman was to get on Missionary Ridge, as he did; Hooker to cross the north end of Lookout Mountain, as he did, sweep across Chattanooga Valley and get across the south end of the ridge near Rossville.

When Hooker had secured that position the Army of the Cumberland was to assault in the centre.

Before Sherman arrived, however, the order was so changed as that Hooker was directed to come to Chattanooga by the north bank of the Tennessee River.